Did you know that Enfield once belonged to Massachusetts? I didn't know until I read the Connecticut State Library's history of the "Southwick Jog." Apparently, the town petitioned to secede because of the high colonial taxes. According to the history, Massachusetts tried to get Enfield back - and failed.
So what does that mean for the genealogist? Probably not much in the day to day. Vital records were kept locally. According to the Connecticut State Library's town and counties list, the town was formed in 1683. The clerk would have started keeping records sometime around that point. Deeds should also have been kept locally, no matter the time period.
Where you may see a difference is in the records kept on the county level. These were only kept in a few sites. Such sites, however, may not be in Connecticut. Court records, military records, and other colonial records may be in Massachusetts. Consider checking with the Massachusetts State Archives for records prior to 1749.